Ultrathin In2O3 Nanosheets toward High Responsivity and Rejection Ratio Visible‐Blind UV Photodetection

Abstract Photoelectrochemical‐type visible‐blind ultraviolet photodetectors (PEC VBUV PDs) have gained ever‐growing attention due to their simple fabrication processes, uncomplicated packaging technology, and high sensitivity. However, it is still challenging to achieve high‐performance PEC VBUV PDs based on a single material with good spectral selectivity. Here, it is demonstrated that individual ultrathin indium oxide (In 2 O 3 ) nanosheets (NSs) are suitable for designing high‐performance PEC VBUV PDs with high responsivity and UV/visible rejection ratio for the first time. In 2 O 3 NSs PEC PDs show excellent UV photodetection capability with an ultrahigh photoresponsivity of 172.36 mA W −1 and a high specific detectivity of 4.43 × 10 11 Jones under 254 nm irradiation, which originates from the smaller charge transfer resistance ( R ct ) at the In 2 O 3 NSs/electrolyte interface. The light absorption of In 2 O 3 NSs takes a blueshift due to the quantum confinement effect, granting good spectral selectivity for visible‐blind detection. The UV/visible rejection ratio of In 2 O 3 NSs PEC PDs is 1567, which is 30 times higher than that of In 2 O 3 nanoparticles (NPs) and exceeds all recently reported PEC VBUV PDs. Moreover, In 2 O 3 NSs PEC PDs show good stability and good underwater imaging capability. The results verify that ultrathin In 2 O 3 NSs have potential in underwater optoelectronic devices.